JPS6144874Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a trochanter escape prevention device for a ball chuck for a sharp pencil.

By tensioning the chuck spring between the chuck body forming the seat of the trochanter and the chuck actuating body forming the inclined receiving surface of the trochanter, the force of the chuck spring can be applied to the above-mentioned inclination. The desired core clamping force is obtained by converting the force in the direction of tightening the chuck part by the action of the receiving surface, and conversely, the core clamping force is achieved by moving the chuck body forward against the force of the chuck spring. Constructions of ball chucks for sharp pencils that weaken and dissipate are known in the art. Usually, the head of this chuck body, that is, the chuck part, has several cracks and is given a self-expanding force in advance, and when the core clamping force weakens or disappears, the self-expanding force is immediately applied. This allows the chuck to expand. However, since there is a natural limit to the degree of expansion, there is a drawback that when inserting a new lead into the chuck, it may get stuck or may not be inserted smoothly. In order to eliminate this drawback, it is necessary to create enough space for the chuck body to fully expand and forcibly expand the chuck body sufficiently. In other words, the mutual positional relationship between the chuck body and the chuck operating body must be The aim is to shift the distance even further compared to . For this purpose, it is necessary to devise a method to prevent the trochanter on the chuck body seat from slipping out from the tip of the chuck operating body. However, if a configuration were adopted in which a member for preventing the escape of the trochanter was provided at the tip of the chuck actuating body, the number of parts would increase and the assembly would be complicated, making it less efficient.

The purpose of this invention is to eliminate the above-mentioned drawbacks, and the details will be explained below with reference to the embodiments shown in the drawings.

The ball chuck of this invention also includes a spring seat 4 of the chuck body 3 which forms the seat 2 of the trochanter 1, and a chuck operating body 6 which forms the inclined receiving surface 5 of the trochanter 1.
A chuck spring 8 is stretched between the chuck body 3 and the spring seat 7 of the chuck body 3, and the chuck spring 8 is stretched between the chuck body 3 and the chuck actuating body 6. Engagement steps 9 and 10 for regulating the mutual positions of the chuck body 3 and the chuck operating body 6 are formed facing each other on the outer and rear side of the chuck body 3, and the engagement steps 9 and 10 of the chuck body 3 and the chuck operating body 6 in that the distance between the front end opening gap between the chuck body 3 and the chuck actuating body 6 is smaller than the diameter of the trochanter 1 when the engagement step portion 10 is engaged.

To assemble the ball chuck as one piece, first fit the chuck spring 8 and the chuck body 3 inside the chuck actuating body 6, and then remove the engaging steps 9, 10.
In this state, while forcibly pressing the divided chuck part toward the center, insert the trochanter 1 into the part, and then insert the next trochanter 1. Assembling can be done relatively easily by intervening in a similar manner. The force equivalent to the pressing force forcefully applied in the direction of the center mentioned above is:
Once assembled, under the operating condition, the trochanter 1 will not fall out prematurely, so even if the two engaging steps 9 and 10 collide, the trochanter 1 will not escape (see FIG. 3).

To assemble it as a sharp pencil, attach the first spring 12 to the front part of the protrusion 11 of the chuck actuating body 6.
The chuck actuating body 6 is biased rearward by the first spring 12 by inserting the fitted body into the shaft cylinder 13 from the front, and then screwing the front shaft body 15 onto the front end of the shaft cylinder 13. , the rear end surface of the protrusion 11 is connected to the shaft cylinder stepped portion 14
so that it occupies a steady rest position.

Centering with a ball chuck and expansion of the chuck part for inserting a new lead into the chuck part are performed by moving the chuck body 3 and the chuck actuating body 6 a certain distance while maintaining a constant mutual positional relationship, and then moving the chuck body 3 to the chuck part 6. For this reason, in this embodiment, the chuck body 3 is moved forward by 3.
A pressing member 18 that is biased rearward by a second spring 16 and movable back and forth by an operating knob 17 exposed outside the shaft cylinder 13 is disposed behind the cylinder.
A pressing arm piece 19 having flexibility is provided which overlaps the chuck actuating body 6 after pressing it forward. As a result, in the first half of the forward movement of the operation knob 17 from FIG. 1 to FIG. The front end surface is pressed against the inner stepped portion 20 of the front shaft body 15. Since the pressing arm piece 19 overlaps the chuck actuating body 6 in the latter half of the forward movement of the operating knob 17 from FIG. 2 to FIG. 3, the arm piece 19 loses its function as a pushing tool. Then, the chuck body 3 can be pushed forward by the pressing member 18. On the other hand,
Since a space is formed that allows the chuck operating body 6 to retreat, the chuck operating body 6 pushed by the first spring 12 can retreat. However, the maximum retraction length is until the engagement step 10 of the chuck operating body 6 hits the engagement step 9 of the chuck body 3.
There is no risk of trochanter 1 prolapse. Further, by moving the chuck body 3 and the chuck operating body 6 in opposite directions, a sufficient clearance is provided between the trochanter 1 and the inclined receiving surface 5 (see FIG. 3). Therefore, as a means for forcibly expanding the chuck part, a protruding engaging part 21 is formed on the front end surface of the chuck body 6, and the other protruding engaging part 22 that cooperates with the protruding engaging part 21 is formed on the front end surface of the chuck body 6. Even if the sliding ring 23 is formed on the body 15 or on the sliding ring 23 that can move back and forth a certain distance with respect to the front shaft body 15 (see Fig. 4), there is sufficient space for expansion, so smooth operation is guaranteed. He will do it for you.

As is clear from the above explanation, this idea is
Engagement step portions 9 and 10 for regulating the mutual positions of the chuck body 3 and the chuck operating body 6, which can prevent the trochanter 1 from escaping.
are formed opposite to the outside of the chuck spring 8 which is tensioned between the chuck body 3 and the chuck actuating body 6, and the engaging step portion 9 of the chuck body 3 and the engaging step portion 10 of the chuck actuating body 6 engage with each other. Since the distance between the front end opening gap between the chuck body 3 and the chuck actuating body 6 is made smaller than the diameter of the trochanter 1, there is no need to use any special member to prevent the trochanter from slipping out. Since the joining parts 9 and 10 are provided at the rear, the chuck body 3 can move forward and the chuck actuating body 6 can move backward, in the opposite direction, without interfering with each other, which is extremely convenient for sufficiently expanding the chuck body. Not only that, but at that time, there is no fear of trochanter 1 falling off.

It goes without saying that the ball chuck trochanter escape prevention device of the present invention may be used in combination with structures other than the illustrated sharp pencil structure, and is by no means limited to the illustrated structure.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of this invention, Figures 2 and 3 are half-cut sectional views showing the operating state, and Figure 4 is a half-cut sectional view when a sliding ring is provided to open the chuck sufficiently. It is. 1... trochanter, 2... catch, 3... check mark,
5... Inclined receiving surface, 6... Chuck operating body, 8...
... Spring for chuck, 9, 10 ... Engagement stepped portion.

Claims (1)

[Scope of utility model registration request] A chuck body 3 forming the seat 2 of the trochanter 1, and a chuck operating body 6 forming the inclined receiving surface 5 of the trochanter 1.
In a ball chuck for a sharp pencil with a chuck spring 8 stretched between the chuck body 3 and
and the chuck actuating body 6, respectively, are provided with engaging step portions 9, 10 for mutual position regulation, facing outward and rearward of the chuck spring 8 stretched between the chuck body 3 and the chuck actuating body 6. When the engaging stepped portion 9 of the chuck body 3 and the engaging stepped portion 10 of the chuck operating body 6 are engaged, the distance between the front end opening gap of the chuck body 3 and the chuck operating body 6 is smaller than the diameter of the trochanter 1. Trochanter escape prevention device for small ball chucks for sharp pencils.